Hi In my system I use sql server 2005 enterprise edition. My db is about 100 gb. I analyzed with DTA and created indexes that is needed but performance didn't improve. when I look execution plan I see a lot of table spools, costant scan, nested loop. what are these and how can I get rid of them? besides I think I have also a problem with recompilation. could you help me about how to prevent recompition?